Archive for the ‘CNC’Category

Former PS:1 president Derek Bever and I were joking in the PS:1 IRC chat room awhile back about using the Shopbot as a tool for uses it was not designed for, and turning it into a plotter seemed especially ridiculous. Since I’d wanted to learn how to use the Clausing lathe, it dawned on me that this ridiculous idea could, in fact, become a terrifying reality. So thanks to Anna Yu who taught me how to use the lathe, I made a bit with an 11mm bore to fit into the 1/2″ collet on the Shoptbot:

Having spent the time to make the part, it seemed silly to stop there, so I realized I’d have to make a post-processor for VCarve and Aspire (Fusion 360 coming soon!). I already had experience with Shopbot’s post-processors, creating a “Always turn spindle off” version of Ryan’s “Always turn spindle on” post processor as well as the XYZ Zero Finder program that works with the XYZ plate made on the Bridgeport. So hunkering down on the computer in the CNC Lounge (where Aspire is installed), I made a “Sharpie Bit” post processor that 1. always turns the spindle off, and 2. always sets Z to 0, regardless of what is done in Aspire or VCarve. This also means you have to explicitly set Z’s 0 position without use of the Z plate as there’s nothing to tell the machine when the ‘bit’ is at the right spot.

The first attempt was made using some cardboard I found in the garbage. This test did not go well because I had set Z to 0 in one corner of the cardboard, but because the cardboard was folded over, it was more puffy in the middle, which means that the Shopbot happily plunged the sharpie into the cardboard. Oops. Try #2 used a piece of acrylic that was laying around and I assumed was garbage, so I used that and the second attempt went much better. Inspired, I grabbed some acrylic from my shelf and made the version below.

I’m going to clean up the code a little (like removing a bunch of debugging stuff, unnecessary pauses, etc.,) and then will run it by Matt (CNC area host) and if he’s cool with it, the bit will go in the drawer and the post processor available to anyone using VCarve and Aspire.

07

05 2017

After months of work, hours of troubleshooting 3D printers and lasers, as well as a lot of patience, I’m proud to present my completed cosplay mask of gynoid Drossel von Flügel. My friend Jaina helped me take pictures at Katsucon last weekend in National Harbor. (Yes, the sameconvention center, unfortunately)

Note: almost all images can be clicked for full size.

I have received no shortage of help from various people. The CNC department at Pumping Station: One has been great at supporting those who want to make things. Twitter user @ByNEET released a full model of Drossel which my friend Faraday (she does 3D work! fortunafaradaze at gmail dot com) helped disassemble for conversion into 3d print friendly STL files. My friends who spent countless late nights with me while I worked on this project. My mom, who was very helpful in assembling the mounts to hold it on my head at the last minute. My friend Amir, who introduced me to Pumping Station: One which has made a huge impact on me. Lastly, the PS:One community itself, for maintaining such a wonderful place to create and share as a community.

Below the read-more is a fairly detailed explanation on how I created the mask and what tools I used for those who are interested in pursing similar projects. Feel free to contact me (Skylar) with questions at SKY at TUNA dot SHor find me at the space! I also have a (photography) website, http://hexbee.net.

28

02 2017

My name is Ralph, and I’m an amateur luthier and PS:1 “starving hacker”.

I make all kinds of instruments: guitars, ukuleles, bouzoukis, and more, but my favorite thing to build is mandolins. They are far and away the most difficult instrument that I make, and require a level of craftsmanship not found in the simpler instruments.

There’s only one real downside to building mandolins— the carving. Mandolin plates are made from 1” thick stock, carved into a very precise dome shape ranging from 3mm thick at the rim up to 6mm thick at the bridge. Making the plate accurately is the key to getting a good tone from the instrument: too thick and it sounds “dead”, too thin and the top can’t withstand the force of the strings.

To make the plates requires a set of inside and outside templates that show the proper curves (making these templates on the laser cutter was a primary reason I joined PS:1), using carving gouges to get close the the final shape, and then curved planes and scrapers to get the dimensions exact. There is about 40-50 hours of carving and scraping that go into a set of mandolin plates. To make things worse, the back plate is made of hard maple, which is VERY difficult to carve. Even with leather carving gloves, my hands are a mess of blisters and callouses after making a plate.

When I saw the CNC routers at PS:1, I was immediately struck by the idea of using CNC to produce a rough mandolin plate. Even if I would still need to scrape to get things perfect, the hard carving work (and blisters) would be taken care of by the machine.

Thus began a year-long journey of discovery…

I learned about CAM, and taught myself to use Fusion 360, only to discover that this 3D modeling stuff is HARD. I managed to turn out some pretty simple models for bridges and headstocks, which I was able to make on the Shapeoko and ShopBot, but every attempt at modeling a mandolin plate failed.

After flailing around for many months, I discovered the Fusion 360 meetup (sponsored by Autodesk and held at PS:1), and everything changed. With the help of Autodesk’s Michael Aubrey (Fusion evangelist), and PS:1’s resident CAD experts, I improved my skills to the point where I was able to make a reasonable model of the top plate for an A-style mandolin.

Last weekend, I got to test the model on the ShopBot! The initial version is in MDF, just to test the model and the machining commands. Once everything is tweaked, I will do the real thing in Sitka spruce.

Since the plate needs to be machined on both sides, I needed to create a fixture to align everything. It’s a pretty straightforward plate, with two alignment pegs that match holes drilled into the ShopBot wasteboard. All of the shaping was done with a 1/2” round-nose bit running at 12000 rpm and a chip load of .35mm.

The inside is machined first, referencing the stock top. It uses a pretty simple adaptive pocket to remove most of the waste, followed by a spiral with a 1mm overlap to take things to the finished size.

You’ll note that the pocket is not centered in the picture— my origin was in the wrong place in my model. I fixed that, and the second attempt came out much better. There is still a bit of scraping/sanding to remove the machine marks, but that was to be expected.

After the inside surface was machined, I flipped the workpiece over and re-registered the Z axis to the bottom of the piece. That way, I know the thickness of the part will be accurate even if my stock thickness is off by a little bit.

Once again an adaptive pocket removed most of the stock, starting with a channel around the rim.

After the rim was rough-sized, the “hump” was roughed in.

A second pass of the adaptive pocket got the rim down to 4mm thick, and smoothed the transitions.

Just as with the inside, the finishing step used a spiral to clean the surface and eliminate the tool marks. The net result was quite good, and will need only a bit of scraping to finish

After all was said and done I swapped in a 1/8” straight bit to cut the outer profile and f-holes.

Cutting off the excess stock left me with a quite nice-looking mandolin top plate! Total elapsed time (not counting my initial screwup) was about 90 minutes.

Putting my micrometer to the finished product, the results were better than I expected. Thickness is accurate within 1mm across the entire profile, with most areas within 0.5mm. That leaves only a bit of scraping to get things perfect!

Next weekend… the real thing, in sitka spruce.

Many thanks to Michael Aubrey from Autodesk, Ray Doeksen and Andrew Carmadella from PS:1, and all of the Fusion 360 Meetup crew that helped me along the way! I’m still a modeling rookie, but I’ve come a LONG way with your help!

Ralph Brendler

10

09 2016

A good friend of mine had the vision to make a memorial to lost cats at Burning Man 2016. It would be a whimsical project with a deeper side to it to honor our fallen feline companions. To see more of what is behind the project can go to see the Spacecats Indiegogo at https://www.indiegogo.com/projects/art-installation-for-burning-man-spacecats#/ . I was asked by her to assist with creating the rocketship part of the project for the intrepid spacecats. I just starting doing CNC work this year and leaped at the opportunity to further improve my skills with a big project. Over a period of 2 months many models were created to arrive at the final form. I will detail the workflow for this and share some of the iterations!

It all started with Fusion 360, a great program for makers, to create a basic rocketship model. Well, I thought it was basic but my inexperience made it a bit harder than expected and went through many hours of “learning time” to arrive at a model I was happy with. From making the 3d model in Fusion 360, I then took it to 123d Make to have it piece together in radial slices so that it can be put together in real life! With the parts generated from 123dMake I was able to create some laser models to show my friend and get her input for her vision. As you can see it took about 4 times to get it right. These models were done 1:10 scale then 1:7 scale. it really helps to have something in front of you to decide what will look best.

After finally arriving at a model that was good it was time to bring it to the shopbot for a 1:2 model (that is also one of the indiegogo rewards!). There was much dialing in to make sure that the slot fit was tight but not too tight to be able to fit the pieces together. Found that adding in .01 helped immensely to get the perfect fit. I did many test notch pieces to ensure the fit. One problem I had was making the test pieces too small so it did not get the full effect of sliding all the way into the wood. I found that making them larger really helped. It paid off to prototype and make test pieces , saved me from wasting many materials , especially when I moved to the more expensive wood! Finally, we had something that the Spacecats seemed somewhat happy about – other than that orange tabby Floyd at least!

Also learned how to use a V bit for this project , very challenging to get the right font in so that it looks nice but was not too thin. This is the plate with the names of departed cats.

And finally , was able to do the full-size model that will go out to burning man! They were displayed at an event last weekend that was a Hawaiian luau, they seemed pretty pleased with it if I do say so myself!

Thanks to everyone at PS:One for the patience to answer many of my questions and excessive use of the shopbot to dial this project in 😀

If curious about the indiegogo project and the other elements of the installation can check out the page at Spacecats . And if going to Black Rock City this year, look for some spacecats in the deep playa!

31

07 2016

I recently completed my most ambitious ShopBot project to date: casting a concrete birdbath bowl in a mold that I CNC’d. This was also my first attempt at producing a video about a project as I’m working on it. Watch the video below:

05

07 2016

by Matt Meshulam posted in CNC, ProjectsComments Off on CNC Birdbath Bowl

Here’s a summary of my coffee table project that many of you have seen me work on (or struggle with) over for the last several months.

I like furniture that can flex or modify it’s position to address different needs. I’ve seen coffee tables that raise to eating height before, but I wanted to design one that really expresses the mechanism and plays up the physics behind it. Back in October I made a 1/2 scale mock up of the design to understand the motion.

Then it was back to designing a full size mock-up.

I realized it wasn’t going to be stable enough with just one set of arms, so I decided two sets would still look good. Everything was designed in Autodesk Revit. The software allows you to figure out volume, then with a given density of materials I could get weights from the various parts. This allowed me to determine the balance. I didn’t want it to be perfectly balanced with the counter-weight, but have enough weight to assist the movement.

First I started making the frame out of aluminum. It’s fastened using a pneumatic riveter.

Painting the steel arms.

CNC cutting the concrete forms out of pink foam

Creating the concrete counter-weight form

Failed attempt to CNC cut aluminum for brackets. I’ll skip the rest of these struggles…

Casting the concrete base

Casting the counterweight (nice and sloppy)

The base assembled.

Frame is attached.

There were many tweaks after testing it. There was some wiggling around the axles, so I widened the holes in the steel arms to put nylon sleeve bearings in for a tighter smoother fit. There was still some shifting after putting some weight on the front, so I designed a locking mechanism with a latch.

Lots of struggle with this latch at the top of the photo. (FYI, learn the cold metals milling machine if you need a part like this)

10

05 2016

I had a plan for how to blog about this project, but I’m going to step out of order and talk about the latest development since it pertains to the last Fusion 360 Meetup. So to catch up in a hurry: I’ve already constructed a control box containing an Arduino Mega 2560 and a Raspberry Pi, power supplies, relays, etc. all mounted on DIN rails. This is the “brains” of the system, and the Pi runs an open source control framework called EPICS. The control box sits on a separate stand on wheels that I welded. In keeping with the “Beer Church” theme, I suppose this is the “Beer Pulpit”.

Beer control box and stand

I realized early on that the control box was out of room. I want this brewing system to be modular so that I can attach different equipment and reconfigure everything via software. To that end, each device needs to connect to the control box with its own sturdy, detachable connector. The original BrewTroller project (which isn’t online anymore) made use of XLR jacks. These are ideal. Nearly every device I’m interfacing with uses 3 or, in some cases, 2 wires. The OneWire serial bus, which is used for measuring temperatures, uses a 3 pin M12 connector; these are chained together using splitters. A few use cases need more than 3 wires: multiple pressure transducers on one board (used for fluid level sensors) and stepper motor drivers (used for controlling gas needle valves). For these, I’m using 8 pin mic connectors. But I don’t have enough panel space on the control box for all of these jacks, especially now that I’m considering adding a small touch screen. Nor do I have room inside the control box to mount a 120 V to 24 V transformer; 24 VAC is a HVAC standard, and the propane burner valves need it.

21

02 2016

Design Sources

A number of commercially available and hobbyist-built computer controlled brewing systems already exist that solve many of the issues I mentioned in my previous post on this topic. They have a number of similarities, but address the problems in different ways. I’m going to describe a number of methods used for computer controlled beer brewing, which improve up0n repeatability by reducing deviations in the mash process. These systems range from simple thermostat / standalone PID controls to microcontroller-based devices. I’ll also list my own design decisions when building this system and my reasoning. Note that my design decisions aren’t necessarily best, there are plenty of valid arguments for and against many of the solutions presented here, and as I write this, I’m kicking myself for some of the mistakes I made along the way.

I’ve examined a number of systems. Our local homebrewing store operates one. I’ve paid particular attention to open source and published plans for hobbyists, given that these offer the most information. Two of my primary sources:

Brutus Ten – Website here. Build pages here and here. This is a popular brewing system due to plans published in Brew Your Own. It consists of a welded steel frame and propane burners driven by standalone industrial temperature control modules.

BrewTroller – The original website was oscsys.com which features an Arduino-based open software and control electronics framework for brewing. The website hosted the software, documentation, a web forum for users, and an online store where one could purchase electronics, actuated valves, switches, temperature probes, etc. It is not locked to any single brewing system design; rather, it is flexible enough to support a wide variety of brewing hardware configurations. While the original site shut down, a user took this over at this site.

28

12 2015

Overview

A bit over a year ago, I began a project to build a computer-controlled beer brewing system that Beer Church (Pumping Station: One’s homebrew club) could use to brew all-grain beer. I had no idea when I started this project that it would lead to visiting people from multiple countries, two synchrotron radiation sources, and a nuclear research reactor, or that control systems engineers from international labs would provide assistance. While it still isn’t ready to brew beer yet, I’ve recently reached a milestone in integration testing, and I’m rapidly approaching the point where the first test batch will be possible. Unfortunately, I haven’t been blogging about it, so a lot of catching up is needed….

So, why would someone want to make what could be called a CNC machine for beer? First, it’s not about eliminating humans. The goal isn’t automation to the level of “push button, get beer.” Humans will still need to load the ingredients and monitor the process. We don’t want a hose breaking, resulting in 12 gallons of beer wort on the floor and a propane burner melting the bottom of the resulting empty stainless steel keg. Rather, the primary reasons are:

Repeatability. I want to eliminate human error. Repeatability often is the domain of commercial brewers, but for hobbyists, repeatability still is critical. Transitioning from good beer to great beer means experimentation. And that requires having good control over all the variables. How do I know if that different yeast I used made my beer taste better, or if it could be explained by sloppy temperature control in the mash process?

Predictability. Shareware and free beer design software exists that acts like CAD for beer. You can design your grain bill based on a library of ingredients, enter a mash and hop schedule, yeast, fermentation temperature, etc. and it will simulate the process, telling you what you can expect in terms of initial and final specific gravity, percent alcohol, color, bitterness, etc. You can tune the model based on the efficiency of your brewing system. But prediction works only as well as the repeatability of your process.

Capacity. Right now, we are limited to 5 gallon batch sizes. While we certainly can buy larger hardware, it makes sense to upgrade to automation at the same time. With a system based on 15.5 gallon beer kegs, we can produce 10 gallon batches at a time.

And, well, there are plenty of secondary reasons that can best be described as “Because hackerspace!” I’ve wanted to learn more about industrial control electronics and the EPICS software environment. It was a great excuse to learn to weld. I had acquired authentic cold war indicator lights from actual nuclear missile systems that needed to be put to an awesome new use. And I could do all that while brewing beer!

To describe the CNC beer system, I first need to explain all-grain brewing and the issues inherent with our current brewing method. To be clear, these issues affect repeatability, not quality. We are already making really good beer. Nothing is wrong with what we’re doing. This new system likely will improve beer clarity (and that is important in homebrewing competitions) but otherwise it won’t do much on its own to make the beer better. Start with a bad recipe and you’ll end up with bad beer; the new hardware just makes it repeatably bad! Rather, it will provide state of the art tools to anyone who wants to experiment, and this could be very useful to brewers wishing to be competitive in homebrewing contests.

25

12 2015

The PS:One ShopBot is a great CNC machine that has the benefit, among other things, of being huge, allowing for a lot of cuts on large pieces of material. One of the difficulties working with the machine, however, is getting the bit at exactly 0,0,0 in the X, Y, and Z axis so that if you need something cut at exactly six inches from the edge of the material, it will be exactly six inches. There is already a built-in method for setting the Z axis, using a metal plate and clip and running a specific program on the ShopBot, but there is no such program for setting the X and Y, requiring the user to manually position the bit. This can lead to inaccuracies and wasted work.

To help everyone with accurate setting of the the X, Y, and Z axis, I made a thing:

The front of the plate, looking down on a test piece of wood for calibration

This is an aluminum plate that is milled to be as precise as I could make it (read: probably a lot of room for improvement) where it sits on the lower left hand corner of the piece to be cut, with the corner of the work sitting directly in the middle of the circle.

With the piece placed on the work, the cable is plugged into the back (I had originally drilled two holes on the front left and bottom of the plate, forgetting that is where the bit has to touch so as to not push the plate off the work, so I drilled a new hold on the back and wrote “Do not use this hole” on the other two) and attached via the alligator clips (ToDo: make a better cable) to the Z plate.

The cable connects the XYZ plate to the Z plate that comes with the Shopbot for finding the Z axis.

The user should position the bit somewhere over the top part of the plate, where doesn’t matter. The user loads xyz-zero-finder.sbp (the code is available at this GitHub repository) into the ShopBot software and runs it. Assuming the bit is somewhere over the top, it will then slowly move the bit down until it touches the top, at which point it will move to the side (visually this appears to be moving towards the front of the machine, but in reality the side of the machine with the power switch is technically the bottom, or X axis). The program will move the bit inside the circle at what it believes is exactly 0,0,0 and, after displaying a message, will move the bit up two inches to allow the user to remove the plate and put it away.

The bit at the corner of the work after the plate has been removed and the bit put back to 0

The plate is in the drawer under the ShopBot in the Arduino box (ToDo: Make a real box for the plate). Feel free to use it and report back how it worked for you, so that we can make it better.

I want to thank Dean, Everett and Todd for giving me valuable advice about how to mill the plate on the Bridgeport; it was tricky because both sides of the plate are milled and getting it to sit properly in the vice was very worrying to me. I also want to thank Eric for suggesting the project in the first place.